In operation, a jigsaw or the like requires a clamp to firmly retain the saw blade during endwise reciprocation of the motor drive shaft. Numerous methods have been employed in an attempt to reliably secure the saw blade within the clamp housing. For example, U.S. Pat. No. 3,781,025 to D'Angelo teaches the use of set screws tightened against opposite sides of the blade, whereas U.S. Pat. No. 4,290,721 to Knoll discloses a variation wherein clamps surrounding the blade are tightened with screws. The first configuration locally deforms the saw blade placing it under excessive strain, and both methods are subject to the loosening of screws due to the reciprocatory motion of the blade. Furthermore, requiring a tool to release and tighten the screws each time a saw blade is to be changed is tedious.
Alternative methods to retain a saw blade, such as those detailed in U.S. Pat. No. 3,583,716 to Daniel, Jr., U.S. Pat. No. 3,823,473 to Hoffman, and U.S. Pat. No. 4,299,402 to Hoffman, have involved the use of blades having apertures or notches which are engaged by pins or cams in order to secure the blade in its inserted position. However, these cutouts compromise the structural integrity of the blade and restrict the form of saw blade capable of being accommodated by each clamp.
Therefore, a blade clamp should be able to accept any arrangement of saw blade without requiring tools to change the blade. To this end, U.S. Pat. No. 4,601,477 to Barrett et al. and published European Patent Application No. EP 0719610A1 to Woodward et al. disclose a blade clamp capable of gripping an unnotched or unapertured blade via contact with a spring-loaded roller, and providing release of the blade through a manual shift of the roller against the spring load. However, the release device used to shift the roller away from the blade either obstructs the field of view or only provides for limited roller movement. Furthermore, the clamp housing lacks durability during periods of extended use.